GB2193526A

GB2193526A - Releasable hook device

Info

Publication number: GB2193526A
Application number: GB08717883A
Authority: GB
Inventors: David Allen Roberts
Original assignee: Lifeguard Equipment Ltd
Current assignee: Lifeguard Equipment Ltd
Priority date: 1986-07-29
Filing date: 1987-07-28
Publication date: 1988-02-10
Anticipated expiration: 2007-07-28
Also published as: GB2193526B; GB8717883D0; GB8618480D0

Abstract

A releasable hook device has a fall attachment portion (10), and a hook (14) pivotally mounted on a mounting portion (18) which is movable relative to the fall attachment portion (10). A hook release latch (20) is also pivotally mounted on the mounting portion (18), and its free end is depressed to disengage its opposite end from the hook (14). When no load is applied to the hook (Fig. 1), two compression springs (38) urge the hook (14) towards the fall attachment portion (10) and the latch (20) may be pivoted to release the hook (14). When a load is applied to the hook (Fig. 3), the springs (38) are compressed causing the latch (20) to move into close proximity with a rigid pin (50) which is releasably secured to portion (10) and which prevents pivoting of the latch (20) and release of the hook (14). However, removal of a retaining means (54) from the pin (50) allows the pin (50) to be withdrawn and thereby allows pivoting of the latch (20) and release of the hook (14). <IMAGE>

Description

SPECIFICATION Releasable hook device The present invention relates to a releasable hook device and in particular, but not exclusively, to a releasable hook device which is used for lifting a boat, life raft or rescue boat off the deck of another boat or ship onto the water.

When a lifeboat is released from a ship, it is lowered from a davit by means of "falls" (suspension ropes). The falls are connected to a pivotally mounted, lockable hook which is hooked onto the lifeboat and locked, forming a closed loop which secures the hook to the lifeboat. The hook is designed such that it may only be unlocked and pivoted to disengage the hooks from the boat when it is in the unloaded state, i.e. when the lifeboat contacts the water. The hook can not be unlocked when it is subjected to a load, i.e.

when the boat is being lowered to the water, lest it be unlocked accidentally, which may cause the boat to fall dangerously into the water.

However, it may sometimes be desirable to release the hook while it is loaded, for example if the lifeboat is trapped in the falls, or if the ship takes a list. However, if the hook is designed to be releasable when loaded, it must be so designed that it can not be accidentally unlocked when subjected to a load, and must be such that it may normally be unlocked only when the hook is not subjected to a load.

It is an object of the present invention to provide a hook release mechanism which is primarily not releasable when in a loaded state, but which can, in an emergency, be operable in that state.

In accordance with the present invention, a releasable hook device comprises a pivotally mounted hook, a latch engageable with the hook to retain the hook in a closed position, the latch being removable, by application of a load to the hook, from a first position in which the latch is displaceable to disengage it from the hook, to a second position in which displacement of the latch is normally restricted by an abutment member, the abutment member being removable upon release of a retaining means to enable the latch to be displaced to disengage it from the hook.

In one embodiment, the hook and latch are pivotally mounted on a mounting member, and the device further comprises a fall attachment portion which is movable relative to the latch by application of a load to the hook, the abutment member being retainable on, and removable from, the fall attachment portion.

Preferably, the device further comprises resiliently deformable biassing means between the fall attachment portion and the mounting member, to bias the latch away from the abutment member.

The abutment member may be in the form of a rigid pin insertable in an aperture in the fall attachment portion, the pin having an enlarged head to prevent it from passing completely through the aperture.

The retaining means may comprise a spring clip which is engageable with a portion of the pin, e.g. a recess in the head of the pin, and/or may comprise a drop nose pin.

The latch may be biassed into engagement with the hook by means of a spring.

By way of example only, a specific embodiment of the present invention will now be described, with reference to the accompanying drawings, in which: Fig. 1 is a cross-sectional side elevation of a first embodiment of releasable hook device in accordance with the present invention, in an unloaded state; Fig.2 is a further cross-section of the hook device of Fig.1, looking in the direction of arrow il-ll of Fig.1; Fig.3 is a cross-sectional side elevation of the hook device of Fig. 1 in a loaded condition; Fig. 4 is a cross-sectional side elevation of a second embodiment of releasable hook device in accordance with a second aspect of the present invention, in an unloaded state; and Fig. 5 is a cross-section of the device of Fig. 4, looking in the direction of arrows V-V in Fig. 4.

Referring firstly to Figs. 1 to 3, the releasable hook device comprises an eye portion 10 for attachment to the falls of a davit and a hook portion 12. The hook portion comprises a hook 14 which is pivotally mounted, by means of a bolt 16, between two, parallel, spaced apart mounting plates 18. A control lever 20 is also pivotally mounted between the mounting plates 18, by means of a bolt 22.The lever 20 is biased in an anticlockwise direction as shown in Fig. 1 by means of a spring 24, having a helical portion mounted on the bolt 22 and which causes an abutment face 26 on the control lever 20 to engage with a corresponding abutment face 28 on the upper portion of the hook 14, thereby holding the hook 14 in the position shown in Fig. 1. One end 24a of the spring 24 is formed perpendicularly to the main portion of the spring and abuts the undersurface of the control lever 20, whereas the other end 24b of the spring 24 is also formed perpendicularly to the main portion of the spring but in the opposite direction to end 24a and is seated in a recess 25 formed in the inner face of the mounting plate 18.

The mounting plates 18 are welded to two upper, parallel, spaced-apart plates 30. The eye portion 10 is provided with a flat, rectangular shank portion 32 which is surrounded by two spring mounting blocks 34 which are slidable thereon. The mounting blocks each comprise a rectangular piece of metal with a rectangular groove whose depth is approxi mately equal to half the width of the shank portion 10, provided in one face thereof.

Thus, by positioning the blocks 34 with the grooves each adjacent to one face of the flat shank portion, and by securing the blocks 34 to the plates 30 by means of bolts 36, the mounting blocks 34 are slidable along the shank portion. The spring mounting blocks 34 are biased upwardly, into the position shown in Fig.1, by means of compression springs 38, one end of which is mounted in adjacent semi-circular recesses 40 in the spring mount ing blocks 34. The movement of the spring mounting blocks in a first direction is limited by the material forming the eye 10, and the movement in the other direction is limited by an enlarged base portion 42 of the shank 32.

The other end of each of the compression springs 38 is located in a recess 44 in a bar -46 which is securely attached to the enlarged head 42 of the eye portion 10 by welding.

One end of the bar 46 extends beyond the lateral extremity of the upper plate 30, and two short, flat elongate parallel bosses 48, 48' project perpendicularly downwardly from said extended end, on either side of the con trol lever 20. It can be seen from Fig.2 that the boss 48' is approximately twice as thick as the boss 48, and that it projects as far as the plate 30.

A metal pin 50 having an enlarged head 52 projects through the bosses 48,48' perpen dicularly to the plane thereof, but is prevented from passing right through the boss 48' by means of the head 52. The pin 50 is held in place firstly by means of a spring clip 54 at tached to the boss 48', the spring clip nor mally being seated in a concave recess 56 in the head 52 of the bolt 50.

The pin 50 is also held in place by means of a drop nose pin 49 mounted on the oppo site end face of the pin 50. The drop nose pin 49 comprises a short lamina 51 which is mounted on a horizontally-orientated pivot pin 53 passing through the pin 50. The lamina 51 projects both above and below the top and bottom of the pin 50, but has a larger portion below the pin 50, so that the lamina assumes the orientation shown in Fig.2, by means of gravity. It should be noted that the pivot pin 53 is always horizontal, since the pin 50 is held in the orientation illustrated, by the spring clip 54. The spring clip 54 also ensures that the head 52 of the pin 50 abuts the boss 48', so that the lamina 51 is spaced apart from the boss 48, which allows the lamina to be pivoted clockwise as shown in Fig.2 without fouling on the boss 48.

In order to unlock the drop nose pin, it is merely necessary to pivot the lamina 51 clockwise as shown in Fig.1, through ninety degrees, so that the lamina 51 lies parallel with the axis of the pin 50, allowing the pin 50 to be withdrawn through the bosses 48,48'.

In use, a hoisting rope is attached through the eye 10, and by pivoting the control lever 20 in a clockwise direction shown in Fig.1, against the force of spring 24, the hook 14 pivots anti-clockwise as shown in Fig.1, and is attached to a boat or other article to be lifted, whereupon the hook 14 is rotated clockwise and is returned to the secured position shown in Fig. 1. This is facilitated by inclined faces 58, 60 on the end of the hook 14 and the end of the control lever 20 respectively. The article may then be raised or lowered as desired.

When there is no load on the hook mechanism, it assumes the configuration shown in Figs. 1 and 2, due to the compression springs 38 separating the mounting blocks 34 and bar 42, and also due to the biassing spring 24 acting on the control lever 20. However, when a load is applied to the hook, for example by lowering a boat towards the water, the load causes the plates 30, the spring mounting portions 34, the mounting plates 18, the hook 14 and the control lever 20 to move downwardly with respect to the eye portion 10, the bar 46, the bosses 48, 48' and the pin 50, against the force of the compression springs 38, into the position illustrated in Fig.3. In this position, the control lever 20 is positioned just above the pin 50, such that if it were desired to release the hook portion 14 by pulling downwardly on the lever 20, this would be prevented by the presence of the pin 50.Thus, it is not possible to operate the lever accidentally when the hook mechanism is in the loaded condition.

However, if for some reason it is necessary to release the hook portion 14 when the hook mechanism is in the loaded position, for example if a boat being lowered were to become entangled in the falls, then this can be done by pushing the spring clip out of engagement with the head 52 of the pin 50, and pivoting the lamina 51 of the drop nose pin 49 through ninety degrees, as explained, allowing the pin 50 to be removed through the bosses 48, 48', and thus permitting the control lever 20 to be operated and the hook to be released. Thus, accidental operation of the control lever when the hook mechanism is in the loaded position is impossible, whereas if it is necessary to operate the control lever when the hook mechanism is in the loaded condition, this can be done by an authorised person.

The second embodiment, illustrated in Figs.

4 and 5 is very similar to the first embodiment, but differs in a few relatively minor features. Firstly, a flexible cable 62 having a knob 64 at its free end is pivotally connected to a pivot 64 at the free end of control lever 20 by means of a lug 66. This enables shorter people to operate the device or, alterna tively, allows the device to be positioned higher up, if necessary.

Secondly, a stop 68 is secured between the mounting plates 18 to restrict the pivotal motion of the hook 14 about the bolt 16. This stop is desirable because without it, if the control lever is released with the falls still under tension, the hook 14 can be rotated to such an extent that it can strike a person's hand in contact with the knob 64 or the control lever 20. The stop 68 prevents this from happening. Also the end 24b of the spring 24 need not now be formed perpendicularly, but may be housed in an elongate aperture 70 in the stop 68.

Finally, in this embodiment the spring clip 54 is dispensed with and the head 52' of the pin 50 has been changed. The head 52 is provided with a cup-shaped collar 72 which provides a seating for one end of a compressed helical compression spring 74 which biasses the pin head 52' away from the boss 48' and biasses the lamina 51 of the drop nose pin 49 into abutment with the boss 48, with the lamina lying substantially vertically.

Accidental removal of the pin 50 is thereby prevented, since in order to remove the pin 50 it is necessary to push the pin head 52 towards the boss 48', against the force of the compression spring 74, which moves the lamina 51 out of abutment with the boss 48 and thereby allows the lamina 51 of the drop head pin, to be rotated through ninety degrees, as for the first embodiment. The pin may then be withdrawn. One end of a short cable 76 is attached to the pin head 52' through an eye 78. The other end is secured to the boss 48' by means of a screw 80 which is screwed into a tapped hole in the boss 48' and whose head bears upon the looped end of the cable.

The withdrawn bolt 50 cannot thus be lost, but instead is held captive by the cable 76 and may be re-used.

The invention is not restricted to the details of the foregoing embodiment. For example, the spring clip 54 or the drop nose pin 49 of the first embodiment may be dispensed with, if required.

Moreover, in the embodiment described, the portions 18, 30 and 34 are welded and/or bolted together, but these may be of onepiece construction instead.

Claims

1. A releasable hook device comprising a pivotally mounted hook, a latch engageable with the hook to retain the hook in a closed position, the latch being movable, by application of a load to the hook, from a first position in which the latch is displaceable to disengage it from the hook, to a second position in which displacement of the latch is normally restricted by an abutment member, the abutment member being removable upon release of a retaining means to enable the latch to be displaced to disengage it from the hook.

2. A device as claimed in claim 1, wherein the latch is pivotally mounted.

3. A device as claimed in claim 2, wherein the hook and the latch are pivotally mounted on a common mounting member.

4. A device as claimed in claim 3, further comprising a fall attachment portion which is movable relative to the common support member by application of a load to the hook.

5. A device as claimed in claim 4, wherein the abutment member is retainable as, and removable from, the fall attachment portion.

6. A deivce as claimed in claim 4 or claim 5, comprising resiliently deformable biassing means between the fall attachment portion and the mounting member, adapted to bias the latch away from the abutment member.

7. A device as claimed in any of claims 4 to 6, wherein the abutment member comprises a rigid pin insertable in an aperture in the fall attachment portion, the pin having an enlarged head.

8. A device as claimed in claim 7, comprising biassing means to bias the pin head towards abutment with the fall attachment portion.

9. A device as claimed in claim 7, comprising biassing means to bias the pin head away from abutment with the fall attachment portion.

10. A device as claimed in any of claims 7 to 9, wherein the end of the pin remote from the pin head is adapted to project out of the aperture and is provided with restraining means which, when the end of the pin is projecting out of the aperture, normally prevents withdrawal of the pin, but is selectively operable to allow withdrawal of the pin.

11. A device as claimed in claim 10, wherein the restraining means comprises a restraining member pivotally mounted on the pin and biassed towards a position in which withdrawal of the pin is prevented.

12. A device as claimed in claim 11, wherein the restraining member is gravitationally biassed.

13. A device as claimed in claim 12, wherein the restraining member comprises a drop nose pin.

14. A releasable hook device substantially as herein described, with reference to, and as illustrated in, Figs. 1 to 3 or Figs. 1 to 3 as modified by Figs. 4 and 5 of the accompanying drawings.